Three-high mill



ay 24, 1938. w. STRINGHAM 318,715

THREE-HIGH MILL Filed Aug. 6, 1935 v INVENTOR.

, M L AM STE/Nahum ATTORNEY S,

aienied ay 24, i

William Strlngham, Fran t. ilhio, assignor to The American Rolling Mill Company, Mlddletown, Ohio, at coration at Ohio Application August 6, 1935, Serial No. 34,937

Claims.

My inventionrelates to the structure of mills known as three high mills, more particularly where the middle roll is small in diameter in comparison with the outer rolls.

5 In such three high mills, particularly where used to roll packs ofsheets it is customary to grind the middle roll with a crown. That is to say, the middle roll isground so that its center is thicker than its ends. The reason for this pracm tice is to eliminate the excessive convexity of the active passes in the mill when in use, due to spring of the rolls therein.

customarily the outer rolls of the mill are ground truly cylindrical although sometimes they are ground hollow, i. e., slightly less in diameter at the middle than at the edges, and sometimes they are slightly "crowned.

The amount of crown or lengthwise convexity of the middle roll will vary with the type of work to be done.

Now in adjusting the screw on the rolls in a three high mill for accurate working, there has been considerable difllculty, due to the fact that if one screw applies more pressure to one end of the middle roll than the other screw applies to its opposite end, the middle roll due to its lengthwise convexity becomes cocked or shifts its position. This changes the shape of the active pass of the mill when in use and seriously afiects the accuracy of operation of the mill on both the lower and the upper pass.

It is the object of my invention to do awaywlth this dimculty, and I accomplish it by forming collars or ridges on both ends of the upper and lower rolls of the mill sufiiicient substantially to equalize the. amount of crown on the middle roll.

I am aware of the fact that in two high mills in order toprevent the surfaces of the rolls from contacting with each other when the mill is no running idle, and to prevent the rolls from be: coming injured when they cometogether alter a piece has passed through them, collars have been formed on the roll ends. My invention does not concern'this idea, nor do I attempt to gain such an effect or to permanently space away the middle roll from all contact with the outer rolls. Indeed the central zone of the middle roll will ordinarily contact the outer rolls when the mill is running idle, according to my invention.

I accomplish my, object bythat certain construction and arrangementsof parts of which an example will be described in detail and has been illustrated in the drawing. The inventive features are set forth in the claims that are ap- 55 pended, to which reference is hereby made.

(or. cc-se In the drawing, the figure is a view partially diagrammatic in nature of a three high mill. The diagrammatic feature is the amount of crown and. height of roll end collar shown, which has been exaggerated for purposes of illustration. 5

I have shown as exemplary housings, the standards l, i, in which the bearings ii, 3 and t are mounted slidably, said bearings serving to rotatably mount the top roll to, the middle roll to and the bottom roll 2a, respectively. 10

The screws 5, serve to adjust the setting of the mill for operation.

It will be noted that the middle roll to is shown to be convex-in longitudinal section. As an example it will hesupposed that the diameter of this roll at the central zone thereof is .015 inch greater than at the ends thereof.

The outer rolls 2a and tar are illustrated as truly cylindrical in shape, and collars or ridges are formedat their ends each collar being ap- 2c protely .0075 inch in height above the surface of the roll. I

It can be seen that with such an arrangement the collars on the ends of the outer rolls will contact with the ends of the middle roll, when the as centers of the outer rolls contact with. the. central crowned zone of the middle roll.

, This accuracy of relationship need not exist but need only be substantially approximated.

Of course the piece being operated upon will so not be wide enough to contact with the collared portion of the outer rolls.

As so arranged there will be no danger of cocking the middleroll upon adjustment of the screws,

no dimculty due to the first screw to be turned v35 down throwing the mill out of transverse adjustment so that the second screw cannot be turned down an equal amount. The dimculty attendant upon rolling of quite wide, thin packs or pieces where accuracy of active pass shape is do of particular importance; has been largely avoided in practice by the use of the abovedescribed simple expedient.

It is desirable to form the collars on the outer rolls rather than the middle roll because in t5 grinding theconvex middle roll to desired shape the machinery normally employed will be interfered with by thecollars. It would, however, be a feasible mode of carrying out my invention to place'the collars on the middleroll.

ving thus described my invention, I will set forth in the following claims the invention inherent therein-upon which I ask for Letters Patent:---

1. In a re high 'mill having a middle mu which is convex in longitudinal section, upper and lower rolls having at the ends collars abuttin against the middle roll and of a height such as substantially to compensate for the greater diameter of the middle roll at its central zone, when the mill is idle, for the purpose described.

2. In a three high mill having a middle roll which is convex in longitudinal section, upper and lower rolls abutting the same at the middle zone thereof, when the mill is idle, the contour of said upper and lower rolls differing from that of the middle roll so as not to be a counterpart thereof, the ends of the respective rolls beyond the working area thereof being such that when the three rolls are brought together at the middle zone thereof, they will abut each other at the ends also.

3. In a three high mill having a middle roll which is convex in longitudinal section and upper and lower non-conforming rolls, the upper and lower rolls so formed at the end beyond the working faces thereof, that when their surfaces substantially abut the middle zone of the middle roll, they will abut the middle roll at the ends thereof also.

4. In a three" high mill having a middle roll which is convex in longitudinal section and upper and lower non-conforming rolls, the said rolls so formed at the ends beyond the working faces thereof, that when their working faces abut at the middle zone, when the mill is idle, they will abut each other at the ends beyond the working faces, at the same time.

5. A three high mill having outer rolls and a middle roll of smaller diameter, said middle roll being convex in longitudinal cross section, and means for preventing misalignment of the rolls upon actuation of the screw down, said means comprising annular raised portions at the ends of the outer rolls of suflicient height to offset the diiference in diameter between the central part of the middle roll and its ends, said raised portions acting to prevent an approach of the ends of the outer rolls to the ends of the middle roll closer than would be permitted by the diameter of the central part of the middle roll without cocking of said roll.

STRINGHAM. 

